Tuesday, June 23, 2009

Writing poor code requires skill

Recently I read an interesting post on decaying code and the various ways that could be adopted in order to improve code quality. It briefly outlined three approaches to improving code (presumably on a code base which has been evolved due to enhancements and bug fixes):
  • Detect the bad code and fix it. But this is too expensive...
  • Don't write it in the first place. But this requires you (or a tool) to be able to spot bad code (consistently) in the first place.
  • Formal Training. This is fine, but how do you ensure that that 'training' is put into practice correctly? And it is all too easy to fall back into bad habits which won't get spotted.
This got me thinking. Are there any other approaches to prevent bad code (or code smells)? Well I reckon there are. In fact it should take skill to write poor code given the amount of help that there is at constructing software now.

Increase use of automatic code generation

When I started programming last century, there were two languages I could choose to write my software in. One was a high-level language and the other was assembly language. While all but the most time critical code was written in the high-level language, I sometimes found it necessary to look at the generated assembly code to understand why my program was failing or to optimise the code. Now, I never look at the object code as I never question the quality of the object code generated by the compilers. However badly the code is written, the compiler would normally ensure that the generated code is efficient; this often means that engineers can get away with sloppy or bad code as it is often automatically refactored in the background
by the compiler to something more optimal. It also encourages, in my opinion, the lazy programmer who understands that the compiler does all the hard work in terms of 'writing' good code.

The increasing use of model driven development (MDD) as part of a model driven architecture (MDA) as a way of improving software productivity is moving the goalposts again. In its purest form, the development uses visual tools and the generated code (in a high level language) and subsequent object code is never seen (by a human). However, I have yet to see any real world MDD which doesn't involve some algorithmic code still being written by hand in a conventional high-level language. Over time, the increasing use of MDD should result in less 'algorithmic' code being written which will, by implication, reduce the potential for less code to decay.

MDD offers the opportunity for engineers to focus on the design rather than the implementation which should result in more maintainable systems which can readily be adapted to include enhancements and changes throughout their life. As the generated code is not the primary artifact which engineers work with, the quality of the generated code becomes less important. However, a key question to consider is does the use of MDD lead to the potential of (over time) of creating a decaying model and if so, how do you prevent it? And can you perform 'bad' MDD?

Reuse (of code snippets)

There are an increasing number of source code repositories (for example see here) now available on the Internet offering a variety of resources from simple algorithms to reusable components. All of these repositories help in providing a (hopefully!) proven way of solving a particular problem, and should also be written in such a way to be readable in case the snippet needs to be tweaked in the future. Although I cannot advocate that the quality of all snippets will meet the criteria of not being 'bad' code, it is reasonable to expect that the many will be examples of 'good' code. If the code snippets can be used 'as is' without modification the code should remain maintainable; if the code is modified, the style of the original code should normally be preserved so that the code remains 'good'.

Although the repositories do not require that the code passes any quality checks with regards maintainability etc, it should become obvious that the better code will be downloaded more frequently.

Use Multiple Compilers

I have always advocated compiling code with two different compilers as a way of improving code quality. No two compilers are ever the same as each one has different strengths and weaknesses. I have also always promoted 'clean' compilation i.e. ensuring that all code compiles without warnings once the set of compile options have been defined. If the code compiles cleanly with two different compilers, there is an increased probability that the code is well-structured, which IMO implies that the code will be more maintainable. It should also help testing as a number of latent faults can often be removed prior to run-time.

Clearly if the multiple compiler approach is adopted, this must be used at all subsequent code evolutions; if not the code will clearly decay albeit more slowly than if a single compiler has been used.


Writing maintainable software requires skill. With a bit of thought (and resisting the temptation to code the first thing that comes into your head), quality code can be produced using one or more of the techniques outlined which will support future product evolutions in a cost effective manner.